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The application of the various building code requirements of ventilation systems in Veterinary Hospitals and Clinics is often misunderstood and misapplied to these types of buildings in our industry. To completely understand the application, a distinct understanding must be had between the building code requirements which represent the minimum design criteria and the industry standards which are more indicative of a practical application or what is known as good engineering practice. This article serves to give an overview of what should be considered when designing these systems.

The governing mechanical code (at the time this article) in New Jersey is the 2018 International Mechanical Code (IMC) with amendments, commonly referred to as the NJ Mechanical Code. IMC Section 403 details ventilation rates for certain occupancies. The IMC does not directly list a category that comports with a Veterinary Hospital or Clinic. One of these occupancies includes “Pet Shops” (Animal Areas), which we suggest be followed for any spaces used for pet care within the facility. Section 403.2.1 (as well as Table 403.3.1.1) details areas that do not permit recirculation of air. The same section further goes on to detail other areas that permit recirculation of air (non-pet care areas) such as offices, restrooms, locker rooms, etc.

A second portion of the IMC that is relative, is Section 502.1, which requires an exhaust system where the processes in such areas produce or throw off dust or particles sufficiently light to float in the air. Furthermore, Section 502.1.3 requires areas that house sources of odors, etc. to be designed and constructed to prevent spreading of such contaminants to other occupied portions of the building.

Although not a cad in New Jersey, but worthy of review as a secondary reference is ASHRAE 62.1, which is a national ventilation standard from which most building codes are built upon. ASHRAE classifies ventilation air (return, transfer, and exhaust) into four different classes where the Class 1 is classified as low-sensory irritation, Class 2 as moderate contaminant concentration, Class 3 as significant contaminant solution, and Class 4 as highly objectionable fumes or gases. ASHRAE limits recirculation of Class 2 air to 10% and Class 3 air to 5%, which are less stringent than the NJIMC requirements, but follows the same approach of not re-circulating air from contaminated spaces.

Also, while not code in New Jersey, reference is made to the Practical Guide for Veterinary Hospital Design. In this guide specific pressure requirements are detailed for dental areas, animal wards, and isolation rooms. These requirements would require exhaust and would most practically involve dedicated outside air. As with the NJIMC, other non-critical areas can be provided with suitable neutral air.

While a Veterinary Hospital and/or Clinic, and the Practical Guide for Veterinary Hospital Design, are clearly different than a “human” medical facility there are gaps in the practical guide occupancy descriptions. We would suggest that these gaps and their requirements run multiple parallel to the AIA Guidelines for Healthcare Facilities with respect to pressure and air exchange rates. Judicious application of the AIA Guidelines to Veterinary Facilities in these instances may be justified.

The system selection and design is further complicated with the need to be able to control humidity in each of the spaces. Humidity levels will vary from operating rooms, wards, as well as office and general spaces. Control of these humidity levels gets complicated with the requisite pressure relationships and ventilation rates in each, along with the increased outside air that is required for these pressure relationships.

From the various code and other reference standards identified herein, one can see that ventilation systems for Veterinary Clinics and Hospitals are just as complicated as conventional Hospitals and require a very similar level of analysis and design. Ventilation systems are typically a combination of 100% outside air systems, dedicated exhaust, and conventional neutral air systems. Aside from an extensively coordinated design, these systems require a thoroughly integrated Building Management System so as to prevent the different systems from running independently and to enable scheduling for the different areas (ie. offices will run on different schedules than operating rooms and wards).

Lastly, in these uncertain times of COVID a properly ventilated space is even more important to ensure a clinical and safe environment. The minimum code requirements should not be the governing criteria and a detailed engineering analysis should be conducted to determine what the appropriate solution for the application should be. Note that most economically designed, or energy efficient system may not be the right system for the space and the referenced considerations should be reviewed before arriving at a final decision with the Owners.

Engineering Humor

Making A List
She’s making a list…
She’s checking it twice…
She’s gonna find out….
How good her memory is, since she got to the store and realized she left it at home… again!

I Asked The Surgeon
I asked the surgeon if I could administer my own anesthetic.
He said, “Sure, knock yourself out!”

Elevator Help
The elevator in our building malfunctioned one day, leaving several of us stranded. Seeing a sign that listed two emergency phone numbers, I dialed the first and explained our situation.
After what seemed to be a very long silence, the voice on the other end said, “I don’t know what you expect me to do for you. I’m a psychologist.”
“A psychologist?” I replied. “Your phone is listed here as an emergency number. Can’t you help us?”
“Well,” he finally responded in a measured tone. “How do you feel about being stuck in an elevator?”

Computer Issues
I told my boss, “Sorry I’m late. I was having computer issues.”
“Hard drive?” he asked.
“No, the commute was fine. It’s my laptop.”

He Replied Too Cheerfully
“Doctor,” said the sick man, “the other doctors seem to differ from you in their diagnosis of my case.”
“I know,” replied the physician cheerfully, “but the post-mortem will show that I am right.”